Low dose oral tobramycin treatment for selective decontamination of the digestive tract: a study in human volunteers

Tobramycin has been given orally to eight human volunteers for four successive days, to investigate its effect on the Gram-negative enterobacilli as well as on the endogenous anaerobic microflora. The effect was investigated in three treatment legs; i.e. in daily doses of 300 mg, in daily doses of 500 mg and thirdly in daily doses of 200 mg in combination with 1000 mg of neomycin. With 300 mg tobra-mycin daily, seven of eight volunteers had no Gram-negative bacilli in their faecal cultures by about four days after the onset of treatment. Their anaerobic micro-flora was slightly affected during treatment as evidenced by the apperance of low concentrations of beta-aspartylglycine in their stools. The other dose regimens were not significantly more effective in eliminating Gram-negative bacilli from the intestines; the anaerobic flora however, was more severely affected. Because evidence of induction of resistance was noticed it is recommended that if tobra-mycin is used for selective decontamination of the intestinal tract it should be given in combination with another antimicrobial drug such as polymyxin